The present application is based on and claims priority from Japanese Patent Application 2000-370684 filed Dec. 5, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a starter for an internal combustion engine and particularly, a starter for a large-sized diesel engine.
2. Description of the Related Art
A starter for a large-sized diesel engine employs a starter motor, a pinion gear to be engaged with a ring gear of a diesel engine and a planetary gear speed reduction mechanism disposed between the starter motor and the pinion gear. The speed reduction mechanism is necessary to provide a compact starter motor. In such a starter, the motor shaft of the starter motor and a pinion drive shaft are not coaxially connected. Usually, the motor shaft is supported by a motor housing, and the pinion drive shaft is supported by a front housing that has a flange which is fixed to a portion of the engine by a fastening bolt. Since the motor shaft and the pinion drive shaft are not coaxially disposed, the motor housing overhangs the flange. Therefore, it is impossible to mount such a starter on the engine by a common socket wrench. It was necessary to use a special tool to mount on or demount from such a starter on the engine.
Therefore, a main object of the invention is to provide a compact starter for an internal combustion engine that can be mounted on an engine easily with a common tool such as a socket wrench.
According to a main feature of the invention, starter for an internal combustion engine includes a planetary gear speed reduction mechanism, a pinion to be engaged with a ring gear of the engine and a pinion drive shaft connected to the speed reduction mechanism, a motor having a motor housing, a front housing for supporting the pinion drive shaft at an end, a center casing for supporting the pinion drive shaft at the other end. The front housing has a flange to be fixed to a portion of the engine. The motor housing has a first outside diameter, and the flange has a plurality of fastening holes disposed at a circumference having a second diameter. The center housing is disposed between the motor housing and the front housing to align a motor shaft, the planetary gear speed reduction mechanism and the pinion drive shaft. A difference between the first outside diameter and the second diameter is larger than a maximum outside diameter of the fastening bolt so that the fastening bolt can be inserted into the fastening hole along the outer periphery of the motor housing.